The objective of this research is to determine the operation of the basic biological mechanisms in the reproductive processes of the female system, particularly as aging alters these processes. Using a species with short lifespan (the golden hamster), we are able to see the aging processes condensed in time and are able to experiment with the organs as their function is altered by age. Uterine function and its interrelation with ovarian function are the present focus of interest, notably in regard to production, uptake, and metabolism of steroid hormones. The methods are divided into the following categories: 1. Uterine steroid binding and metabolism. 2. Uterine decidual reaction after treatment with progesterone or metabolites. 3. Measurement of circulating and tissue steroid levels. 4. Histochemistry of ovaries and uteri.